The importance of determining certain conditions in a well bore are well known. For example, it is important that the drilling fluids or drilling mud used during drilling operations continually circulate through the system at a given density or weight.
It is important to know the density of the drilling fluids used. When the density is below that desired, a blowout of the well may occur because formation gases are mixed with the drilling fluid. When the density of the mud is above that desired, the efficiency of the drilling operation becomes impaired because of the undesired, unnecessary mud weight.
Further, if the drilling fluids or mud is flowing out into formations, the well is said to be taking a "drink" because of lost circulation. This condition is extremely important because loss of circulating fluid reduces the hydrostatic head in the well bore which increases the probability of a blowout.
The prior art is representatively disclosed by U.S. Pat. Nos. 3,532,502, 2,229,986, 3,550,696, 3,740,739 3,613,806, 3,833,076, 3,384,175, 2,674,695, and 2,323,128, all of which discloses inventions relating to measuring levels of fluids or drilling mud systems.
In accordance with the invention, a device for and method of sensing conditions across a well bore is disclosed which includes a radioactive source positioned adjacent the surface of the well bore to emit a radioactive signal across the well bore, a detection means for detecting the signal after transmission through fluids in the well bore, electrical means for amplifying the detected signal, and means for actuating suitable mud pumps to add drilling fluid as desired, and means for actuating alarm systems, if desired to indicate the absence of drilling fluids.